Role of VAMP1 in synaptic transmission and Alzheimer's dementia

摘要 阿尔茨海默病(AD)是导致痴呆症的主要原因之一，影响着数以百万计的老年患者 因此，这是一个严峻的卫生保健挑战。目前可用的药物可能会提供一些 暂时缓解，但它们都不能阻止疾病的发展或治愈。开发更好的治疗方法 迫切需要对这种疾病的病因有明确的了解。最近的数据表明，突触的比率 囊泡内吞作用的活性和速率对淀粉样前体的加工至关重要。 蛋白质(APP)转化为β-淀粉样蛋白(Abeta)，这是AD中主要有毒成分的来源。确切的分子 将突触传递与APP处理联系起来的机制仍不清楚。我的实验室是长期的 目标是在大脑中找到新的分子治疗靶点(S)，它可以帮助防止突触功能障碍 和神经退化来保存认知和记忆。这个应用程序的目标是检查一个 一类特殊的蛋白质--囊泡膜相关蛋白(VAMPS/Synaptobrevins)及其作用 在突触释放和Abeta的产生中。我们强有力的初步结果建立了Synaptobrevin1/VAMP1 (Syb1)是SNARE(SNAP受体)复合体的成员，作为这项创新性研究的新对象 痴呆：A)在人类遗传学中筛查VAMP1基因的单核苷酸多态(SNP)变体 编码syb1与晚发性AD显著相关；b)SNP与表达增加相关 VAMP1基因的缺失增加了AD的风险，而与VAMP1低表达相关的SNPs降低了AD的风险； C)在新的VAMP1KO小鼠中，内源性Abeta40和Abeta42水平显著降低。基于 这些观察结果，中心假设是VAMP1是囊泡释放之间的关键偶联蛋白 和应用程序处理。我们假设VAMP1水平的变化改变了突触的耦合 传播到应用程序处理，因此对Abeta生产有深远影响。该计划的基本原理 建议的研究是，了解激活Abeta产生的分子机制将提供 一种新的、更好的降低Abeta水平的方法，它可能防止或延缓AD患者的认知能力下降。我们会 通过追求三个具体目标来检验这一假设：1)检验突触短缩蛋白表达水平对 使用新型VAMP1KO小鼠的神经元的突触活性和Abeta的产生。2)识别结构 VAMP1的元件将突触活动耦合到APP加工的淀粉样蛋白形成途径。3)评估 降低VAMP1水平对预防AD模型Tg2576小鼠体内认知功能障碍的影响。 这些目标将通过对突触活性、内吞作用和Abeta产生的广泛分析来测试 采用复杂的方法，包括多电极和膜片钳电生理学和实时荧光 显微镜。这项拟议的研究意义重大，因为它有可能将VAMP1确定为第一个 淀粉样蛋白生成的突触调节因子和AD诊断和治疗的新靶点。

Abstract Alzheimer’s disease (AD) is a major cause of dementia, affecting millions of elderly patients in our aging society, and thus represents a severe health care challenge. Currently available drugs may provide some temporary relief but none of them is able to halt disease progression or cure. To develop better therapies a clear understanding of the disease etiology is urgently needed. Recent data suggest the rate of synaptic activity and particularly rate of vesicle endocytosis is critically important for the processing of amyloid precursor protein (APP) into beta-amyloid (Abeta), a source of major toxic component in AD. The exact molecular mechanism connecting synaptic transmission to APP processing is still unknown. My laboratory’s long-term goal is to identify new, molecular therapeutic target(s) in the brain that can help to prevent synaptic dysfunction and neurodegeneration to preserve cognition and memory. The objective in this application is to examine a specific class of proteins – the vesicular membrane associated proteins (VAMPs/synaptobrevins) and their role in synaptic release and Abeta production. Our strong preliminary results establish synaptobrevin1/VAMP1 (syb1), a member of the SNARE (SNAP Receptor) complex, as a novel object for this innovative research of dementia: a) in human genetic screens single nucleotide polymorphism (SNP) variants of the VAMP1 gene encoding syb1 are significantly associated with late onset AD; b) SNPs associated with increased expression of VAMP1 increase the risk of AD and SNPs associated with lower VAMP1 expression reduces the risk of AD; c) in the new VAMP1 KO mice endogenous Abeta40 and Abeta42 levels are substantially reduced. Based on these observations, the central hypothesis is that VAMP1 is a key coupling protein between vesicular release and APP processing. We hypothesize that variations in VAMP1 level alter the coupling of synaptic transmission to APP processing and therefore have profound effect on Abeta production. The rationale for the proposed research is that understanding the molecular mechanism that activates Abeta production will provide a novel, better way to lower Abeta levels and it may prevent or delay cognitive decline in AD patients. We will test this hypothesis by pursuing three specific aims: 1) Examine the effect of synaptobrevin expression level on synaptic activity and Abeta production in neurons using the novel VAMP1 KO mice. 2) Identify the structural elements of VAMP1 coupling synaptic activity to amyloidogenic pathway of APP processing. 3) Evaluate the effects of reduced VAMP1 levels on preventing cognitive impairment in the AD model Tg2576 mice in vivo. These aims will be tested through extensive analysis of synaptic activity, endocytosis and Abeta production with sophisticated methods including multi-electrode and patch-clamp electrophysiology and live fluorescence microscopy. The proposed research is significant because it has the potential to identify VAMP1 as the first synaptic regulator of amyloidogenesis and novel target for AD diagnosis and therapy.